Circle surface area

How is circular surface area values square rooted ??. I am using this formula r2Xπ=mm2 to calculate the surface area of a circle but i want to know if there is a formula to get back to the diameter or the radius of the circle ?.

example i have a circular surface area of 5.26mm2 and i want the diameter of that value, how do i solve this ?

Staff: Mentor

We don't call it "surface area" - just area. Surface area applies to surfaces in three dimensions. For objects in the plane (two dimensions), we talk about the area.

magmash said:

I am using this formula r2Xπ=mm2

The actual formula is ##A = \pi r^2##. If r is given in mm., then the units of area will be square millimeters or mm2. The formula shouldn't explicitly show units.

magmash said:

to calculate the surface area of a circle but i want to know if there is a formula to get back to the diameter or the radius of the circle ?.

From the equation ##A = \pi r^2##, to get the radius, solve for r. To do this, divide both sides of the equation by ##\pi##, then take the square root. Once you have the radius r, you can get the diameter using d = 2r.

magmash said:

example i have a circular surface area of 5.26mm2 and i want the diameter of that value, how do i solve this ?